Can menthol help athletes cope with heat?

Dr Russ Best explains how swilling menthol, or applying it to the body, can help athletes cope with heat when racing in hot and humid conditions

Can menthol help athletes cope with heat?

Even if the Covid pandemic doesn’t prevent the already postponed Tokyo Olympics from taking place in 2021, triathletes face another natural threat – the heat. Temperatures will be into the 30s, meaning the globe’s finest sports scientists and coaches will be preparing their cohorts to perform in this extreme environment. Cue heat chambers, hydration strategies and, according to Dr Russ Best of the Waikako Institute of Technology in New Zealand, menthol.

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“I know of organisations who are working on innovative ways of incorporating menthol into their heat acclimation and performance strategies,” says the Englishman. “Tokyo will be a great catalyst for menthol use in tri, and we’ll see an increase in products on the market post-Olympics.”

Best’s PhD thesis was termed ‘Menthol mouth swilling and endurance running performance in the heat’. Best showed that runners enjoyed ‘better thermal comfort’ and ‘lower oxygen consumption’ after swilling menthol mouth rinse (light blue or green preferred) – both desirable in the heat.

How does menthol work?

But how? “Menthol affects TRPM8 receptors, which detect cold temperatures and hence mimic this temperature range,” says Best. “The perceptual effect of this is we may feel more comfortable, or less hot or thirsty. Physiologically, this can increase our ventilation, redirecting blood away from the skin and alleviating sensations of pain.”

Best says you can either swill mouthwash or apply menthol to your skin. “Menthol mouth rinsing has been shown to increase time to exhaustion, while there’s evidence that a menthol spray is more about improving thermal perception. It may even preserve body temperature when applied as a cream in high concentrations, which may be of interest to open-water swimmers when training in the cold.”

For a few years now, triathletes have contacted Best about best menthol practice, and he has this advice for those of you racing the likes of Kona, Alpe d’Huez Tri or even July’s Outlaw. “We’ve supported Ironman athletes with menthol and used it as an adjunct to the athletes’ feeding strategy on the bike. This helps to combat flavour fatigue due to over-consumption of carbohydrate drinks and snacks. At 0.1% concentration, we’ve found the perceptual effects last around 15mins, so alternating carbohydrate drinking and menthol swilling will help how you feel during a hot triathlon.”

Yet there are caveats. Applying too much over a large area of the body may lead to heatstroke as the menthol masks the dangers of heat and a rising core temperature, while you should start in small quantities if you’ve never rinsed with menthol before.

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As for the future, Best is looking to investigate menthol’s effects during higher-intensity work as much of the current research has centred on endurance efforts below VO2max. “We also need to explore the co-ingestion of menthol and more established sports nutrition strategies, and possibly look at how we prime the system to be responsive to menthol, whether this be through timing, temperature or applying alternate tastants like chilli to heighten the perceptual and physiological responses to menthol.”